Method and apparatus for signal transmission in wireless communication system

ABSTRACT

Provided are a method and an apparatus for signal transmission in a wireless communication system. The apparatus comprises: an information processor for generating a first information sequence based on a first transmission symbol and a first resource index, and a second information sequence based on a second transmission symbol and a second resource index; a reference signal generator for generating a different reference signal depending upon whether a first resource block indicated by the first resource index and a second resource block indicated by the second resource index are the same; and an antenna for transmitting a signal generated based on the first information sequence, the second information sequence, and the reference signal sequence.

CROSS-REFERENCE TO RELATED APPLICATIONS

This application is a continuation of U.S. patent application Ser. No.13/128,867, filed on May 11, 2011, now U.S. Pat. No. 8,908,793, which isthe National Stage filing under 35 U.S.C. 371 of InternationalApplication No. PCT/KR2009/006696, filed on Nov. 13, 2009, which claimsthe benefit of U.S. Provisional Application Nos. 61/118,473, filed onNov. 27, 2008, 61/117,237, filed on Nov. 24, 2008, 61/116,298, filed onNov. 20, 2008, 61/115,113, filed on Nov. 17, 2008, 61/114,481, filed onNov. 14, 2008, and 61/114,479, filed on Nov. 14, 2008, the contents ofwhich are all hereby incorporated by reference herein in their entirety.

BACKGROUND OF THE INVENTION

Field of the Invention

The present invention relates to wireless communications, and moreparticularly, to a method and apparatus for signal transmission in awireless communication system.

Related Art

Wireless communication systems are widely spread all over the world toprovide various types of communication services such as voice or data.The wireless communication system is designed for the purpose ofproviding reliable communication to a plurality of users irrespective oftheir locations and mobility. However, a wireless channel has anabnormal characteristic such as a fading phenomenon caused by a pathloss, noise, and multipath, an inter-symbol interference (ISI), aDoppler effect caused by mobility of a user equipment, etc. Therefore,various techniques have been developed to overcome the abnormalcharacteristic of the wireless channel and to increase reliability ofwireless communication.

A multiple input multiple output (MIMO) scheme is used as a techniquefor supporting a reliable high-speed data service. The MIMO scheme usesmultiple transmit antennas and multiple receive antennas to improve datatransmission/reception efficiency. Examples of the MIMO scheme includespatial multiplexing, transmit diversity, beamforming, etc. A MIMOchannel matrix depending on the number of receive antennas and thenumber of transmit antennas can be decomposed into a plurality ofindependent channels. Each independent channel is referred to as atransmission layer or a stream. The number of transmission layers isreferred to as a rank.

Meanwhile, there is an ongoing standardization effort for aninternational mobile telecommunication-advanced (IMT-A) system aiming atthe support of an Internal protocol (IP)-based multimedia seamlessservice by using a high-speed data transfer rate of 1 gigabits persecond (Gbps) in a downlink and 500 megabits per second (Mbps) in anuplink in the international telecommunication union (ITU) as a nextgeneration (i.e., post 3^(rd) generation) mobile communication system. A3^(rd) generation partnership project (3GPP) is considering a 3GPP longterm evolution-advanced (LTE-A) system as a candidate technique for theIMT-A system. It is expected that the LTE-A system is developed tofurther complete an LTE system while maintaining backward compatibilitywith the LTE system. This is because the support of compatibilitybetween the LTE-A system and the LTE system facilitates userconvenience. In addition, the compatibility between the two systems isalso advantageous from the perspective of service providers since theexisting equipment can be reused.

A typical wireless communication system is a single-carrier systemsupporting one carrier. Since a data transfer rate is in proportion to atransmission bandwidth, the transmission bandwidth needs to increase tosupport a high-speed data transfer rate. However, except for some areasof the world, it is difficult to allocate frequencies of widebandwidths. For the effective use of fragmented small bands, a spectrumaggregation technique, also referred to as bandwidth aggregation orcarrier aggregation, is being developed. The spectrum aggregationtechnique is a technique for obtaining the same effect as when a band ofa logically wide bandwidth is used by aggregating a plurality ofphysically non-contiguous bands in a frequency domain. By using thespectrum aggregation technique, multiple carriers can be supported inthe wireless communication system. The wireless communication systemsupporting the multiple carriers is referred to as a multiple-carriersystem. The multiple-carrier system is also referred to as a carrieraggregation system. The carrier may also be referred to as other terms,such as, a radio frequency (RF), a component carrier (CC), etc.

Time division multiplexing (TDM), frequency division multiplexing (FDM),code division multiplexing (CDM), or the like can be used as amultiplexing scheme for communication between a base station and each ofa plurality of user equipments. The CDM and/or the FDM may be used forsimultaneous communication between the base station and each of theplurality of user equipments.

A resource for wireless communication is any one or more combinations of(1) time, (2) frequency, and (3) sequence according to a multiplexingscheme. However, to increase an amount of information that istransmitted concurrently, it may be necessary to allocate multipleresources to one user equipment (UE). When allocating the multipleresources, a problem may arise in a method of transmitting a signal suchas an information signal and a reference signal by using the multipleresources.

Accordingly, there is a need for a method and apparatus for effectivesignal transmission.

SUMMARY OF THE INVENTION

The present invention provides a method and apparatus for signaltransmission in a wireless communication system.

In an aspect, a transmitter including an information processorconfigured for generating a first information sequence based on a firsttransmission symbol and a first resource index, and configured forgenerating a second information sequence based on a second transmissionsymbol and a second resource index, a reference signal generatorconfigured for generating a different reference signal sequencedepending upon whether a first resource block indicated by the firstresource index is identical to a second resource block indicated by thesecond resource index, and an antenna for transmitting a signalgenerated based on the first information sequence, the secondinformation sequence, and the reference signal sequence is provided.

In another aspect, a method for signal transmission performed by atransmitter in a wireless communication system is provided. The methodinclude generating a first information sequence based on a firsttransmission symbol and a first resource index, and generating a secondinformation sequence based on a second transmission symbol and a secondresource index, generating a different reference signal sequencedepending upon whether a first resource block indicated by the firstresource index is identical to a second resource block indicated by thesecond resource index, and transmitting a signal generated based on thefirst information sequence, the second information sequence, and thereference signal sequence.

According to the present invention, an effective informationtransmission method and apparatus are provided in a wirelesscommunication system. Therefore, an overall system performance can beimproved.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 shows a wireless communication system.

FIG. 2 is a diagram showing a radio protocol architecture for a userplane.

FIG. 3 is a diagram showing a radio protocol architecture for a controlplane.

FIG. 4 shows a structure of a radio frame.

FIG. 5 shows an example of a resource grid for one UL slot.

FIG. 6 shows a structure of a DL subframe.

FIG. 7 shows an exemplary structure of a UL subframe.

FIG. 8 is a block diagram showing an exemplary structure of atransmitter. Herein, the transmitter may be a part of a UE or a BS.

FIG. 9 is a block diagram showing an exemplary structure of aninformation processor included in a transmitter.

FIG. 10 shows an example of PUCCH format 1/1a/1b transmission in case ofa normal CP.

FIG. 11 shows an example of PUCCH format 1/1a/1b transmission in case ofan extended CP.

FIG. 12 shows an example of PUCCH format 2 transmission when a normal CPis used.

FIG. 13 shows an example of PUCCH format 2 transmission when an extendedCP is used.

FIG. 14 is a block diagram showing an exemplary structure of atransmitter including two antennas.

FIG. 15 is a block diagram showing an exemplary structure of a part of atransmitter including two antennas.

FIG. 16 is a block diagram showing an exemplary structure of a part of atransmitter including a single antenna.

FIG. 17 shows another example of a case where a 1^(st) RB is differentfrom a 2^(nd) RB.

FIG. 18 shows an example in which a 1^(st) RB is identical to a 2^(nd)RB.

FIG. 19 is a block diagram showing another exemplary structure of a partof a transmitter including two antennas.

FIG. 20 is a block diagram showing wireless communication system toimplement an embodiment of the present invention.

DESCRIPTION OF EXEMPLARY EMBODIMENTS

Techniques described below can be used in various multiple accessschemes such as code division multiple access (CDMA), frequency divisionmultiple access (FDMA), time division multiple access (TDMA), orthogonalfrequency division multiple access (OFDMA), single carrier frequencydivision multiple access (SC-FDMA), etc. The SC-FDMA is a scheme inwhich inverse fast Fourier transform (IFFT) is performed oncomplex-valued symbols subjected to discrete Fourier transform (DFT)spreading, and is also referred to as DFT spreading-orthogonal frequencydivision multiplexing (DFTS-OFDM). In addition, the techniques describedbelow can also be used in a multiple access scheme modified from theSC-FDMA, for example, clustered SC-FDMA, NxSC-FDMA, etc. The clusteredSC-FDMA is a scheme in which complex-valued symbols subjected to DFTspreading are divided into a plurality of sub-blocks and the pluralityof sub-blocks are distributed in a frequency domain and are mapped tosubcarriers. The clustered SC-FDMA is also referred to as clusteredDFTS-OFDM. The NxSC-FDMA is a scheme in which a code block is dividedinto a plurality of chunks and DFT and IFFT are performed on a chunkbasis. The NxSC-FDMA is also referred to as chunk specific DFTS-OFDM.

The CDMA may be implemented as a radio technology such as universalterrestrial radio access (UTRA) or CDMA2000. The TDMA may be implementedas a radio technology such as a global system for mobile communications(GSM)/general packet radio service (GPRS)/enhanced data rates for GSMevolution (EDGE). The OFDMA may be implemented by a radio technologysuch as IEEE (Institute of Electrical and Electronics Engineers) 802.11(Wi-Fi), IEEE 802.16 (WiMAX), IEEE 802.20, E-UTRA (Evolved UTRA), andthe like. The UTRA is part of a universal mobile telecommunicationssystem (UMTS). 3GPP (3^(rd) Generation, Partnership Project) LTE (LongTerm Evolution) is part of an evolved UMTS (E-UMTS) using the E-UTRA,which employs the OFDMA in downlink and the SC-FDMA in uplink. LTE-A(Advanced) is an evolution of 3GPP LTE.

Hereinafter, for clarification, 3GPP LTE/LTE-A will be largelydescribed, but the technical concept of the present invention is notmeant to be limited thereto.

FIG. 1 shows a wireless communication system.

Referring to FIG. 1, a wireless communication system 10 includes atleast one base station (BS) 11. Respective BSs 11 provide communicationservices to specific geographical regions (generally referred to ascells) 15 a, 15 b, and 15 c. The cell can be divided into a plurality ofregions (referred to as sectors). A user equipment (UE) 12 may be fixedor mobile, and may be referred to as another terminology, such as amobile station (MS), a user terminal (UT), a subscriber station (SS), awireless device, a personal digital assistant (PDA), a wireless modem, ahandheld device, etc. The BS 11 is generally a fixed station thatcommunicates with the UE 12 and may be referred to as anotherterminology, such as an evolved node-B (eNB), a base transceiver system(BTS), an access point, etc.

Hereinafter, a downlink (DL) implies communication from the BS to theUE, and an uplink (UL) implies communication from the UE to the BS. Inthe DL, a transmitter may be a part of the BS, and a receiver may be apart of the UE. In the UL, the transmitter may be a part of the UE, andthe receiver may be a part of the BS.

A heterogeneous network implies a network in which a relay station, afemto cell and/or a pico cell, and the like are deployed. In theheterogeneous network, the DL may imply communication from the BS to therelay station, the femto cell, or the pico cell. Further, the DL mayalso imply communication from the relay station to the UE. Furthermore,in case of multi-hop relay, the DL may imply communication from a firstrelay station to a second relay station. In the heterogeneous network,the UL may imply communication from the relay station, the femto cell,or the pico cell to the BS. Further, the UL may also imply communicationfrom the UE to the relay station. Furthermore, in case of multi-hoprelay, the UL may imply communication from the second relay station tothe first relay station.

The wireless communication system can support multiple antennas. Thetransmitter may use a plurality of transmit (Tx) antennas, and thereceiver may use a plurality of receive (Rx) antennas. The Tx antennadenotes a physical or logical antenna used for transmission of onesignal or stream. The Rx antenna denotes a physical or logical antennaused for reception of one signal or stream. When the transmitter and thereceiver use a plurality of antennas, the wireless communication systemmay be referred to as a multiple input multiple output (MIMO) system.

The wireless communication system can support UL and/or DL hybridautomatic repeat request (HARQ). In addition, a channel qualityindicator (CQI) can be used for link adaptation.

A wireless communication process is preferably implemented with aplurality of independent hierarchical layers rather than one singlelayer. A structure of a plurality of hierarchical layers is referred toas a protocol stack. The protocol stack may refer to an open systeminterconnection (OSI) model which is a widely known protocol forcommunication systems.

FIG. 2 is a diagram showing a radio protocol architecture for a userplane. FIG. 3 is a diagram showing a radio protocol architecture for acontrol plane. The user plane is a protocol stack for user datatransmission. The control plane is a protocol stack for control signaltransmission.

Referring to FIGS. 2 and 3, between different physical (PHY) layers(i.e., a PHY layer of a transmitter and a PHY layer of a receiver), datais transferred through a physical channel. The PHY layer is alsoreferred to as a layer 1 (L1). The PHY layer is coupled with a mediumaccess control (MAC) layer, i.e., an upper layer of the PHY layer,through a transport channel. Between the MAC layer and the PHY layer,data is transferred through the transport channel. The PHY layerprovides the MAC layer and an upper layer with an information transferservice through the transport channel.

The MAC layer provides services to a radio link control (RLC) layer,i.e., an upper layer of the MAC layer, through a logical channel. TheRLC layer supports reliable data transmission. A packet data convergenceprotocol (PDCP) layer performs a header compression function to reduce aheader size of an Internet protocol (IP) packet. The MAC layer, the RLClayer, and the PDCP layer are also referred to as a layer 2 (L2).

A radio resource control (RRC) layer is defined only in the controlplane. The RRC layer is also referred to as a layer 3 (L3). The RRClayer controls radio resources between a UE and a network. For this, inthe RRC layer, RRC messages are exchanged between the UE and thenetwork. The RRC layer serves to control the logical channel, thetransport channel, and the physical channel in association withconfiguration, reconfiguration and release of radio bearers. The radiobearer represents a logical path provided by the L1 and the L2 for datatransmission between the UE and the network. Configuration of the radiobearer implies a process for defining characteristics of a radioprotocol layer and channel to provide a specific service, and forconfiguring respective specific parameters and operation mechanisms. Theradio bearer can be classified into a signaling radio bearer (SRB) and adata radio bearer (DRB). The SRB is used as a path for transmitting anRRC message in the control plane, and the DRB is used as a path fortransmitting user data in the user plane. When an RRC connection isestablished between an RRC layer of the UE and an RRC layer of thenetwork, it is called that the UE is in an RRC connected mode. When theRRC connection is not established yet, it is called that the UE is in anRRC idle mode.

A non-access stratum (NAS) layer belongs to an upper layer of the RRClayer and serves to perform session management, mobility management, orthe like.

FIG. 4 shows a structure of a radio frame.

Referring to FIG. 4, the radio frame consists of 10 subframes. Onesubframe consists of two slots. Slots included in the radio frame arenumbered with slot numbers #0 to #19. A time required to transmit onesubframe is defined as a transmission time interval (TTI). The TTI maybe a scheduling unit for data transmission. For example, one radio framemay have a length of 10 milliseconds (ms), one subframe may have alength of 1 ms, and one slot may have a length of 0.5 ms.

The radio frame of FIG. 4 is shown for exemplary purposes only. Thus,the number of subframes included in the radio frame or the number ofslots included in the subframe may change variously.

FIG. 5 shows an example of a resource grid for one UL slot.

Referring to FIG. 5, the UL slot includes a plurality of orthogonalfrequency division multiplexing (OFDM) symbols in a time domain andincludes N(UL) resource blocks (RBs) in a frequency domain. The OFDMsymbol represents one symbol period, and may also be referred to asother terms such as an OFDMA symbol, an SC-FDMA symbol, or the likeaccording to a multiple access scheme. The number N(UL) of RBs includedin the UL slot depends on a UL transmission bandwidth determined in acell. One RB includes a plurality of subcarriers in the frequencydomain.

Each element on the resource grid is referred to as a resource element(RE). The RE on the resource grid can be identified by an index pair (k,l) in a slot. Herein, k(k=0, . . . , N(UL)×12-1) denotes a subcarrierindex in the frequency domain, and l(l=0, . . . , 6) denotes a symbolindex in the time domain.

Although it is described herein that one RB includes 7×12 resourceelements consisting of 7 OFDM symbols in the time domain and 12subcarriers in the frequency domain for example, the number of OFDMsymbols and the number of subcarriers in the RB are not limited thereto.Thus, the number of OFDM symbols and the number of subcarriers maychange variously depending on a cyclic prefix (CP) length, a frequencyspacing, etc. For example, when using a normal CP, the number of OFDMsymbols is 7, and when using an extended CP, the number of OFDM symbolsis 6.

The resource grid for one UL slot of FIG. 5 can also be applied to aresource grid for a DL slot.

FIG. 6 shows a structure of a DL subframe.

Referring to FIG. 6, the DL subframe includes two consecutive slots.First 3 OFDM symbols of a 1^(st) slot included in the DL subframecorrespond to a control region, and the remaining OFDM symbolscorrespond to a data region. Herein, the control region includes 3 OFDMsymbols for exemplary purposes only.

A physical downlink shared channel (PDSCH) may be allocated to the dataregion. DL data is transmitted through the PDSCH. The DL data may be atransport block which is a data block for a downlink shared channel(DL-SCH), i.e., a transport channel transmitted during TTI. A BS maytransmit the DL data to a UE through one antenna or multiple antennas.In 3GPP LTE, the BS may transmit one codeword to the UE through oneantenna or multiple antennas, or may transmit two codewords throughmultiple antennas. The 3GPP LTE supports up to 2 codewords. Thecodewords are encoded bits in which channel coding is performed on aninformation bit corresponding to information. Modulation can beperformed for each codeword.

A control channel may be allocated to the control region. Examples ofthe control channel include a physical control format indicator channel(PCFICH), a physical hybrid automatic repeat request (HARQ) indicatorchannel (PHICH), a physical downlink control channel (PDCCH), etc.

The PCFICH carries information indicating the number of OFDM symbolsused for transmission of PDCCHs in a subframe to the UE. The number ofOFDM symbols used for PDCCH transmission may change in every subframe.In the subframe, the number of OFDM symbols used for PDCCH transmissionmay be any one value among 1, 2, and 3. If a DL transmission bandwidthis less than a specific threshold, the number of OFDM symbols used forPDCCH transmission in the subframe may be any one value among 2, 3, and4.

The PHICH carries HARQ acknowledgement (ACK)/negative acknowledgement(NACK) for UL data.

The control region consists of a set of a plurality of control channelelements (CCEs). If a total number of CCEs constituting a CCE set isN(CCE) in the DL subframe, the CCEs are indexed from 0 to N(CCE)-1. TheCCEs correspond to a plurality of resource elements groups. The resourceelement group is used to define mapping of the control channel to aresource element. One resource element group consists of a plurality ofresource elements. A PDCCH is transmitted through an aggregation of oneor several contiguous CCEs. A plurality of PDCCHs may be transmitted inthe control region. A PDCCH format and the number of available PDCCHbits are determined according to the number of CCEs constituting the CCEaggregation. Hereinafter, the number of CCEs used for PDCCH transmissionis referred to as a CCE aggregation level. The CCE aggregation level isa CCE unit for searching for the PDCCH. A size of the CCE aggregationlevel is defined by the number of contiguous CCEs. For example, the CCEaggregation level may be an element of {1, 2, 4, 8}.

The PDCCH carries DL control information. Examples of the DL controlinformation include DL scheduling information, UL schedulinginformation, a UL power control command, etc. The DL schedulinginformation is also referred to as a DL grant. The UL schedulinginformation is also referred to as a UL grant.

The BS does not provide the UE with information indicating where a PDCCHof the UE is located in the subframe. In general, in a state where theUE does not know a location of the PDCCH of the UE in the subframe, theUE finds the PDCCH of the UE by monitoring a set of PDCCH candidates inevery subframe. Monitoring implies that the UE attempts to performdecoding for each of the PDCCH candidates according to all possible DCIformats. This is referred to as blind decoding or blind detection.

For example, when the BS transmits the DL data to the UE through a PDSCHwithin a subframe, the BS carries a DL grant used for scheduling of thePDSCH through a PDCCH within the subframe. The UE can first detect thePDCCH for transmitting the DL grant through blind decoding. The UE canread the DL data transmitted through the PDSCH based on the DL grant.

FIG. 7 shows an exemplary structure of a UL subframe.

Referring to FIG. 7, the UL subframe can be divided into a controlregion and a data region. A physical uplink control channel (PUCCH) forcarrying UL control information is allocated to the control region. Aphysical uplink shared channel (PUSCH) for carrying user data isallocated to the data region. In 3GPP LTE (Release 8), resource blocksallocated to one UE are contiguous in a frequency domain to maintain asingle-carrier property. One UE cannot transmit the PUCCH and the PUSCHconcurrently. Concurrent transmission of the PUCCH and the PUSCH isunder consideration In LTE-A (Release 10).

The PUCCH for one UE is allocated in a resource block (RB) pair in thesubframe. RBs belonging to the RB pair occupy different subcarriers ineach of 1^(st) and 2^(nd) slots. A frequency occupied by the RBsbelonging to the RB pair to be allocated to the PUCCH is changed on aslot boundary basis. That is, RBs allocated to the PUCCH are hopped in aslot level. Hereinafter, hopping of the RB in the slot level is calledfrequency hopping. A frequency diversity gain is obtained when the UEtransmits UL control information through a frequency located atdifferent positions over time. In FIG. 7, m is a location indexindicating a frequency-domain location of the RB pair allocated to thePUCCH within the subframe.

The PUSCH is mapped to an uplink shared channel (UL-SCH) which is atransport channel. Examples of UL control information transmittedthrough the PUCCH include HARQ ACK/NACK, a channel quality indicator(CQI) indicating a DL channel state, a scheduling request (SR) as arequest for UL radio resource allocation, etc. Hereinafter, the CQI isthe concept including a precoding matrix indicator (PMI) and a rankindicator (RI) in addition to the CQI.

Time division multiplexing (TDM), frequency division multiplexing (FDM),code division multiplexing (CDM), or the like can be used as amultiplexing scheme for communication between a BS and each of aplurality of UEs. The CDM and/or the FDM may be used for simultaneouscommunication between the BS and each of the plurality of UEs.

Multiplexing schemes based on an orthogonal sequence or aquasi-orthogonal sequence are collectively referred to as the CDM. Thatis, sequences used for the CDM are not necessarily orthogonal to eachother. Sequences having a low correlation may also be used for the CDM.

Hereinafter, a method and apparatus for information transmission will bedescribed when CDM and/or FDM are used as a multiplexing scheme.

When the CDM and/or the FDM are used as the multiplexing scheme, aresource used for information transmission is a sequence and/or afrequency resource. For example, when only the CDM is used as themultiplexing scheme, the resource is the sequence, and when the CDM andthe FDM are used together, the resource is the sequence and thefrequency resource. Hereinafter, the frequency resource and the sequencewill be described in detail.

(1) Frequency Resource

The aforementioned resource block is an example of the frequencyresource. This is because the frequency resource differs when theresource block differs within the same time period. Hereinafter, forconvenience of explanation, the resource block is used in the concept ofa normal frequency resource.

(2) Sequence

The sequence is not particularly limited, and thus may be any sequence.

For example, the sequence may be selected from a sequence set having aplurality of sequences as its elements. The plurality of sequencesincluded in the sequence set may be orthogonal to each other, or mayhave a low correlation with each other. For convenience of explanation,it is assumed that the plurality of sequences included in the sequenceset are orthogonal to each other. Hereinafter, the sequence set is anorthogonal sequence set consisting of orthogonal sequences. Each of theorthogonal sequences belonging to the orthogonal sequence setcorresponds to one orthogonal sequence index in a one-to-one manner.

The orthogonal sequence set having length-4 orthogonal sequences as itselements may use a Walsh-Hadamard matrix. Table 1 below shows an exampleof an orthogonal sequence set consisting of an orthogonal sequence w(k,los) having a length of K=4 (los denotes an orthogonal sequence indexand k denotes an element index of the orthogonal sequence, where0≦k≦K−1).

TABLE 1 Orthogonal sequence index [w(0), w(1), w(2), w(3)] 0 [+1 +1 +1+1] 1 [+1 −1 +1 −1] 2 [+1 +1 −1 −1] 3 [+1 −1 −1 +1]

The orthogonal sequence set may consist of only some orthogonalsequences of Table 1 above. In 3GPP LTE, three orthogonal sequences areused except for [+1, +1, −1, −1].

Table 2 below shows an example of an orthogonal sequence set consistingof an orthogonal sequence w(k, los) having a length of K=3 (los denotesan orthogonal sequence index and k denotes an element index of theorthogonal sequence, where 0≦k≦K−1).

TABLE 2 Orthogonal sequence Index [w(0), w(1), w(2)] 0 [1 1 1] 1 [1e^(j2π/3) e^(j4π/3)] 2 [1 e^(j4π/3) e^(j2π/3)]

Table 3 below shows an example of an orthogonal sequence set consistingof an orthogonal sequence w(k, los) having a length of K=2 (los denotesan orthogonal sequence index and k denotes an element index of theorthogonal sequence, where 0≦k≦K−1).

TABLE 3 Orthogonal sequence index [w(0), w(1] 0 [1 1] 1 [1 −1]

For another example, a cyclically shifted sequence may be used as thesequence. The cyclically shifted sequence can be generated by cyclicallyshifting a base sequence by a specific cyclic shift (CS) amount. Varioustypes of sequences can be used as the base sequence. For example, awell-known sequence such as a pseudo noise (PN) sequence and aZadoff-Chu (ZC) sequence can be used as the base sequence.Alternatively, a computer generated constant amplitude zeroauto-correlation (CAZAC) sequence may be used. Equation 1 below shows anexample of the base sequence.r _(i)(n)=e ^(jb(n)π/4)  [Equation 1]

Herein, iε{0, 1, . . . , 29} denotes a root index, and n denotes acomponent index in the range of 0≦n≦N−1, where N is a sequence length. ican be determined by a cell identifier (ID), a slot number in a radioframe, etc. When one resource block includes 12 subcarriers, N can beset to 12. A different base sequence is defined according to a differentroot index. When N=12, b(n) can be defined by Table 4 below.

TABLE 4 i b(0), . . . , b(11) 0 −1 1 3 −3 3 3 1 1 3 1 −3 3 1 1 1 3 3 3−1 1 −3 −3 1 −3 3 2 1 1 −3 −3 −3 −1 −3 −3 1 −3 1 −1 3 −1 1 1 1 1 −1 −3−3 1 −3 3 −1 4 −1 3 1 −1 1 −1 −3 −1 1 −1 1 3 5 1 −3 3 −1 −1 1 1 −1 −1 3−3 1 6 −1 3 −3 −3 −3 3 1 −1 3 3 −3 1 7 −3 −1 −1 −1 1 −3 3 −1 1 −3 3 1 81 −3 3 1 −1 −1 −1 1 1 3 −1 1 9 1 −3 −1 3 3 −1 −3 1 1 1 1 1 10 −1 3 −1 11 −3 −3 −1 −3 −3 3 −1 11 3 1 −1 −1 3 3 −3 1 3 1 3 3 12 1 −3 1 1 −3 1 1 1−3 −3 −3 1 13 3 3 −3 3 −3 1 1 3 −1 −3 3 3 14 −3 1 −1 −3 −1 3 1 3 3 3 −11 15 3 −1 1 −3 −1 −1 1 1 3 1 −1 −3 16 1 3 1 −1 1 3 3 3 −1 −1 3 −1 17 −31 1 3 −3 3 −3 −3 3 1 3 −1 18 −3 3 1 1 −3 1 −3 −3 −1 −1 1 −3 19 −1 3 1 31 −1 −1 3 −3 −1 −3 −1 20 −1 −3 1 1 1 1 3 1 −1 1 −3 −1 21 −1 3 −1 1 −3 −3−3 −3 −3 1 −1 −3 22 1 1 3 −3 −3 −3 −1 3 −3 1 −3 3 23 1 1 −1 −3 −1 −3 1−1 1 3 −1 1 24 1 1 3 1 3 3 −1 1 −1 −3 −3 1 25 1 −3 3 3 1 3 3 1 −3 −1 −13 26 1 3 −3 −3 3 −3 1 −1 −1 3 −1 −3 27 −3 −1 −3 −1 −3 3 1 −1 1 3 −3 −328 −1 3 −3 3 −1 3 3 −3 3 3 −1 −1 29 3 −3 −3 −1 −1 −3 −1 3 −3 3 1 −1

The base sequence r(n) can be cyclically shifted according to Equation 2below to generate a cyclically shifted sequence r(n, Ics).

$\begin{matrix}{{{r\left( {n,I_{cs}} \right)} = {{r(n)} \cdot {\exp\left( \frac{{j2\pi}\; I_{cs}n}{N} \right)}}},{0 \leq I_{cs} \leq {N - 1}}} & \left\lbrack {{Equation}\mspace{14mu} 2} \right\rbrack\end{matrix}$

In Equation 2, Ics denotes a CS index indicating a CS amount (0≦Ics≦N−1,where Ics is an integer).

Hereinafter, an available CS index of the base sequence denotes a CSindex that can be derived from the base sequence according to a CSinterval. For example, if a length of the base sequence is 12 and the CSinterval is 1, a total number of available CS indices of the basesequence is 12. Alternatively, if a length of the base sequence is 12and the CS interval is 2 a total number of available CS indices of thebase sequence is 6. The CS interval can be determined by considering adelay spread.

FIG. 8 is a block diagram showing an exemplary structure of atransmitter. Herein, the transmitter may be a part of a UE or a BS.

Referring to FIG. 8, a transmitter 100 includes an information processor110, a reference signal generator 120, a resource block mapper 130, anOFDM signal generator 140, a radio frequency (RF) unit 150, and anantenna 190.

The information processor 110 and the reference signal generator 120 areconnected to the resource block mapper 130. The resource block mapper130 is connected to the OFDM signal generator 140. The OFDM signalgenerator 140 is connected to the RF unit 150. The RF unit 150 isconnected to the antenna 190.

Information is input to the information processor 110. Examples of theinformation include user data, control information, mixed information ofseveral pieces of control information, multiplexed information of thecontrol information and the user data, etc. The information may have abit or bit-stream format. The transmitter 100 can be implemented in aphysical layer. In this case, the information may be derived from ahigher layer such as a MAC layer.

The information processor 110 is configured to generate an informationsequence based on information or a sequence. The information sequenceconsists of a plurality of information sequence elements. Theinformation sequence can also be referred to as an information signal.

FIG. 9 is a block diagram showing an exemplary structure of aninformation processor included in a transmitter.

Referring to FIG. 9, an information processor 110 includes a channelcoding unit 111, a modulator 112, and an information sequence generator113.

An information bit corresponding to information to be transmitted by thetransmitter is input to the channel coding unit 111. The channel codingunit 111 performs channel coding on the information bit to generate anencoded bit. There is no restriction on a channel coding scheme.Examples of the channel coding scheme include turbo coding, convolutioncoding, block coding, etc. The block code may be a Reed-Muller codefamily. A size of the encoded bit output from the channel coding unit111 may be various.

The modulator 112 maps an encoded bit to a symbol that expresses aposition on a signal constellation to generate a modulation symbol.There is no restriction on a modulation scheme. Examples of themodulation scheme include m-phase shift keying (m-PSK), m-quadratureamplitude modulation (m-QAM), etc. The number of modulation symbolsoutput from the modulator 112 may be various according to the size ofthe encoded bit input to the modulator 112 and the modulation scheme.

The information processor 110 may (or may not) perform discrete Fouriertransform (DFT) on the modulation symbol. When performing DFT, theinformation processor 110 may further include a DFT unit (not shown) foroutputting a complex-valued symbol by performing DFT on the modulationsymbol. It is assumed herein that the modulation symbol is directlyinput to the information sequence generator 113 without performing DFT.Hereinafter, the modulation symbol input to the information sequencegenerator 113 implies a complex-valued symbol corresponding toinformation to be transmitted by the transmitter 100.

The information sequence generator 113 generates an information sequencebased on an information symbol or sequence. The information sequence maybe a one-dimensional spread sequence or a two-dimensional spreadsequence.

(1) One-Dimensional Spread Sequence

The one-dimensional spread sequence is generated based on a modulationsymbol and a 1^(st) sequence. One modulation symbol or each of aplurality of modulation symbols may be multiplied by the 1^(st) sequenceto generate the one-dimensional spread sequence.

Equation 3 below shows an example of generating K one-dimensional spreadsequences s(n) based on modulation symbols d(0), . . . , d(K−1) and a1^(st) sequence x(n) with a length N (K and N are natural numbers, and nis an element index of the 1^(st) sequence, where 0≦n≦N−1).s(n)=d(k)x(n), 0≦k≦K−1  [Equation 3]

In Equation 3, the modulation symbols d(0), . . . , d(K−1) may be Kmodulation symbols. Alternatively, one modulation symbol d(0) may berepetitively used K times.

The one-dimensional spread sequence s(n) is mapped to a time domain or afrequency domain. When it is mapped to the time domain, theone-dimensional spread sequence s(n) may be mapped to time samples,chips, or OFDM symbols. When it is mapped to the frequency domain, theone-dimensional spread sequence s(n) may be mapped to subcarriers.

Hereinafter, when the one-dimensional spread sequence s(n) is mapped tothe time domain, the 1^(st) sequence x(n) is called a time-domainsequence. When the one-dimensional spread sequence s(n) is mapped to thefrequency domain, the 1^(st) sequence x(n) is called a frequency-domainsequence.

(2) Two-Dimensional Spread Sequence

The two-dimensional spread sequence is generated based on theone-dimensional spread sequence and a 2^(nd) sequence. That is, thetwo-dimensional spread sequence is generated based on the modulationsymbol, the 1^(st) sequence, and the 2^(nd) sequence. Theone-dimensional spread sequence may be spread to the 2^(nd) sequence togenerate the two-dimensional spread sequence.

Equation 4 below shows an example of generating a two-dimensional spreadsequence z(n,k) by spreading K one-dimensional spread sequences s(n) toa 2^(nd) sequence y(k) (k is an element index of the 2^(nd) sequence,where 0≦k≦K−1).z(n,k)=w(k)y(n)=w(k)d(k)x(n)  [Equation 4]

The two-dimensional spread sequence z(n,k) is mapped to the time domainor the frequency domain. For example, n may correspond to a subcarrierindex, and k may correspond to a symbol index. Alternatively, n maycorrespond to a symbol index, and k may correspond to a subcarrierindex.

Referring back to FIG. 8 again, the reference signal generator 120generates a reference signal sequence. The reference signal sequenceconsists of a plurality of reference signal elements. The referencesignal sequence can also be referred to as a reference signal (RS). TheRS is a signal which is known to both a transmitter and a receiver. TheRS can be used for information demodulation in the receiver. Anysequence can be used as the RS sequence without a particularrestriction.

An RS sequence may be generated similarly to generation of aninformation sequence. When the information sequence is theone-dimensional spread sequence, the 1^(st) sequence for an RS may beused as the RS sequence. If the information sequence is thetwo-dimensional spread sequence, the RS sequence may be generated basedon the 1^(st) sequence for the RS and the 2^(nd) sequence for the RS.

The resource block mapper 130 is configured to map the informationsequence and the RS sequence to a resource block allocated forinformation transmission. One information sequence element or one RSsequence element can be mapped to one resource element. Since CDM isused, multiplexing can be achieved to the same resource block. Ofcourse, FDM can be used together with the CDM, and thus multiplexing canbe achieved by different resource blocks.

One or more resource blocks may be used for information transmission.The resource block includes an information part and an RS part. Theinformation sequence is mapped to the information part, and the RSsequence is mapped to the RS part.

The RS part and the information part may use different OFDM symbolswithin a resource block. Alternatively, the RS part and the informationpart may use different subcarriers within an OFDM symbol.

For convenience of explanation, it is assumed hereinafter that the RSpart and the information part use different OFDM symbols within theresource block. One or more OFDM symbols within the resource block maybe the RS part. When a plurality of OFDM symbols within the resourceblock correspond to the RS part, the plurality of OFDM symbols may becontiguous to each other or may be non-contiguous to each other. Theposition and number of OFDM symbols used as the RS part within theresource block may vary without a particular restriction. An OFDM symbolwithin the resource block except for the RS part may be used as theinformation part.

For example, it is assumed that the transmitter is a part of a UE, andtransmits information through a PUCCH. The resource block mapper 130maps the information sequence and the RS sequence to a resource blockpair (see FIG. 7) within a subframe allocated for PUCCH transmission.

The OFDM signal generator 140 is configured to generate atime-continuous OFDM signal in every OFDM symbol within the resourceblock. The time-continuous OFDM signal is also referred to as an OFDMbaseband signal. The OFDM signal generator 140 can generate an OFDMsignal by performing an inverse fast Fourier transform (IFFT) operation,CP insertion, or the like for each OFDM symbol.

The RF unit 150 converts the OFDM baseband signal to a radio signal. TheOFDM baseband signal can be converted to the radio signal by beingup-converted to a carrier frequency. The carrier frequency is alsoreferred to as a center frequency.

The radio signal is transmitted through the antenna 190.

As such, to perform information transmission, the transmitter 100 has todetermine a resource used for information transmission. The resource mayconsist of at least one of (1) the 1^(st) sequence, (2) the 2^(nd)sequence, and (3) resource blocks. For example, the 1^(st) sequence maybe a cyclic shifted sequence, and the 2^(nd) sequence may be anorthogonal sequence.

A resource index identifies the resource used for informationtransmission. Therefore, the resource is determined from the resourceindex. Each of sequences used to generate the information sequence andthe RS sequence is determined from the resource index. In addition, aresource block to which the information sequence and the RS sequence aremapped can be determined from the resource index.

Therefore, the transmitter 100 has to obtain the resource index toperform information transmission. When the transmitter is a part of aBS, the transmitter may determine the resource index through scheduling.

When the transmitter is a part of a UE, a method of obtaining theresource index of the UE is problematic. The BS may report the resourceindex to the UE explicitly or implicitly. In addition, the resourceindex may change semi-statically or dynamically.

For example, the resource index may be determined by higher layersignaling. The higher layer may be an RRC layer. In this case, theresource index changes semi-statically. Information to be transmitted bythe UE may be SR, semi-persistent scheduling (SPS) ACK/NACK, CQI, etc.The SPS ACK/NACK is HARQ ACK/NACK for DL data transmitted throughsemi-static scheduling. When the DL data is transmitted through a PDSCH,a PDCCH corresponding to the PDSCH may not exist.

For another example, the UE may obtain the resource index from a radioresource by which a control channel for receiving the DL data istransmitted. In this case, information transmitted by the UE may bedynamic ACK/NACK. The dynamic ACK/NACK is ACK/NACK for DL datatransmitted through dynamic scheduling. In the dynamic scheduling, theBS transmits a DL grant to the UE every time through a PDCCH whenever DLdata is transmitted through the PDSCH.

Equation 5 below shows an example of determining a resource index R fordynamic ACK/NACK transmission.R=n(CCE)+N(PUCCH)  [Equation 5]

In Equation 5, n(CCE) denotes a 1^(st) CCE index used for PDCCHtransmission with respect to a PDSCH, and N(PUCCH) denotes the number ofresource indices allocated for SR and SPS ACK/NACK. N(PUCCH) is acell-specific parameter, and can be determined by a higher layer such asan RRC layer.

Therefore, the BS can regulate a resource for ACK/NACK transmission bycontrolling the 1^(st) CCE index used for PDCCH transmission.

As an example of an information transmission method based on CDM andFDM, there is a method transmitting UL control information through aPUCCH. Hereinafter, the method of transmitting the UL controlinformation through the PUCCH will be described.

The PUCCH can support multiple formats. That is, it is possible totransmit the UL control signal whose number of bits per subframe differsaccording to the modulation scheme. Table 5 below shows an example of amodulation scheme and the number of bits per subframe based on a PUCCHformat.

TABLE 5 PUCCH Modulation Number of bits format scheme per subframe 1 N/A N/A 1a BPSK 1 1b QPSK 2 2  QPSK 20 2a QPSK + BPSK 21 2b QPSK + QPSK22

The PUCCH format 1 is used to transmit the SR. The PUCCH format 1a/1b isused to transmit the HARQ ACK/NACK signal. The PUCCH format 2 is used totransmit the CQI. The PUCCH format 2a/2b is used to transmit the CQI andthe HARQ ACK/NACK signal.

In any subframe, if the HARQ ACK/NACK signal is transmitted alone, thePUCCH format 1a/1b is used, and if the SR is transmitted alone, thePUCCH format 1 is used. The UE can transmit the HARQ ACK/NACK signal andthe SR simultaneously in the same subframe. For positive SRtransmission, the UE transmits the HARQ ACK/NACK signal by using a PUCCHallocated for the SR. For negative SR transmission, the UE transmits theHARQ ACK/NACK signal by using a PUCCH resource allocated for theACK/NACK.

In case of the PUCCH format 1a, an ACK/NACK bit (one bit) is output froma channel coding unit. For example, each ACK may be coded to a binary‘1’, and each NACK may be coded to a binary ‘0’. In case of the PUCCHformat 1b, ACK/NACK bits (two bits) b(0) and b(1) may be output from thechannel coding unit. b(0) may correspond to an ACK/NACK bit for a 1^(st)codeword, and b(1) may correspond to an ACK/NACK bit for a 2^(nd)codeword. That is, the PUCCH format 1a is for HARQ ACK/NACK informationfor the 1^(st) codeword, and the PUCCH format 1b is for HARQ ACK/NACKinformation of the 2^(nd) codeword.

Each of the PUCCH formats 1, 1a, and 1b uses one complex-valued symbold(0). The BS can detect an SR by only determining whether there is PUCCHformat 1 transmission from the UE. That is, an on-off keying (OOK)modulation scheme can be used in SR transmission. Therefore, any complexvalue can be used as a value of the modulation symbol d(0) for the PUCCHformat 1. For example, d(0)=1 may be used. The modulation symbol d(0)for the PUCCH format 1a is a modulation symbol generated when an encodedbit (1 bit) is modulated by using binary phase shift keying (BPSK). Thecomplex-valued symbol d(0) for the PUCCH format 1b is a modulationsymbol generated when encoded bits (2 bits) are modulated by usingquadrature phase shift keying (QPSK).

Table 6 below shows an example of a modulation symbol to which anACK/NACK bit is mapped according to a modulation scheme.

TABLE 6 Modulation scheme Bit(s) d(0) BPSK 0  1 1 −1 QPSK 00  1 01 −j 10 j 11 −1

FIG. 10 shows an example of PUCCH format 1/1a/1b transmission in case ofa normal CP. Although it is expressed herein that resource blocksbelonging to a resource block pair occupy the same frequency band in a1^(st) slot and a 2^(nd) slot, the resource blocks can be hopped in aslot level as described with reference to FIG. 7.

Referring to FIG. 10, the 1^(st) slot and the 2^(nd) slot each include 7OFDM symbols. Among the 7 OFDM symbols included in each slot, 3 OFDMsymbols correspond to an RS part to which an RS sequence is mapped, andthe remaining 4 OFDM symbols correspond to an information part to whichan information sequence is mapped. The RS part corresponds to 3contiguous OFDM symbols located in the middle of each slot. The positionand number of OFDM symbols used as the RS part in each slot may vary,and thus the position and number of OFDM symbols used as the informationpart may also vary.

In the information part, an information sequence is generated based on amodulation symbol d(0), a cyclically shifted sequence r(n,Ics), and anorthogonal sequence w(k, los). The cyclically shifted sequence r(n,Ics)may also be referred to as a 1^(st) sequence, and the orthogonalsequence w(k, los) may also be referred to as a 2^(nd) sequence.Therefore, the information sequence is a two-dimensional spreadsequence. By spreading information to a time-space domain, UEmultiplexing capacity can be increased. The UE multiplexing capacity isthe number of UEs that can be multiplexed to the same resource block.

The cyclically shifted sequence r(n,Ics) is generated from a basesequence for each OFDM symbol used as the information part within thesubframe. The base sequence is identical within one slot. The 1^(st)slot and the 2^(nd) slot may have identical or different base sequenceswithin the subframe. The cyclically shifted index Ics is determined froma resource index. The cyclically shifted index Ics can be CS-hopped in asymbol level. Hereinafter, hopping of a CS index in the symbol level iscalled CS hopping. The CS hopping can be performed according to a slotnumber n(s) within a radio frame and a symbol index I within a slot.Therefore, the CS index Ics can be expressed by Ics(n(s),I). CS hoppingcan be performed in a cell-specific manner to randomize inter-cellinterference. In FIG. 10, the value Ics for each OFDM symbol in theinformation part is for exemplary purposes only.

A 1^(st) sequence s(n) spread in a frequency domain is generated foreach OFDM symbol of the information part on the basis of the modulationsymbol d(0) and the cyclically shifted sequence r(n,Ics). The 1^(st)sequence s(n) can be generated by multiplying the modulation symbol d(0)by the cyclically shifted sequence r(n,Ics) according to Equation 6below.s(n)=d(0)r(n,I _(cs))  [Equation 6]

An information sequence spread to a time-frequency domain is generatedon the basis of the 1^(st) sequence s(n) generated for each OFDM symbolof the information part and the orthogonal sequence w(k, los) having alength of K=4. The 1^(st) sequence may be spread in a block type byusing the orthogonal sequence w(k, los) to generate the informationsequence. Elements constituting the orthogonal sequence correspond toOFDM symbols of the information part sequentially in a one-to-onemanner. Each of the elements constituting the orthogonal sequence ismultiplied by the 1^(st) sequence s(0) mapped to its corresponding OFDMsymbol to generate the information sequence.

The information sequence is mapped to a resource block pair allocated toa PUCCH within the subframe. The resource block pair is determined fromthe resource index. After the information sequence is mapped to theresource block pair, IFFT is performed on each OFDM symbol of thesubframe to output a time-domain signal. Although the orthogonalsequence is multiplied before IFFT is performed in this case, the sameresult can also be obtained when the 1^(st) sequence s(n) is mapped tothe resource block pair and thereafter the orthogonal sequence ismultiplied.

When a sounding reference signal (SRS) and the PUCCH formats 1/1a/1b areconcurrently transmitted in one subframe, one OFDM symbol on the PUCCHis punctured. For example, a last OFDM symbol of the subframe may bepunctured. In this case, in the 1^(st) slot of the subframe, the controlinformation consists of 4 OFDM symbols. In the 2^(nd) slot of thesubframe, the control information consists of 3 OFDM symbols. Therefore,the orthogonal sequence having the spreading factor K=4 is used for the1^(st) slot, and the orthogonal sequence having the spreading factor K=3is used for the 2^(nd) slot.

An orthogonal sequence los is determined from the resource index. Theorthogonal sequence index los may be hopped in a slot level.Hereinafter, hopping of the orthogonal sequence index in the slot levelis referred to as orthogonal sequence (OS) remapping. The OS remappingcan be performed according to the slot number n_(s) within the radioframe. Therefore, the orthogonal sequence index los can be expressed bylos(n_(s)). The OS remapping may be performed to randomize inter-cellinterference.

In the RS part, the RS sequence is generated on the basis of thecyclically shifted sequence r(n,I′cs) and the orthogonal sequence w(k,I′os) having a length of K=3. I′cs denotes a CS index for the RS, andI′os denotes an orthogonal sequence index for the RS. I′cs and I′os aredetermined from respective resource indices. A cyclically shiftedsequence is a frequency-domain sequence, and an orthogonal sequence is atime-domain sequence. Therefore, the RS sequence is a sequence which isspread to a time-frequency domain similarly to the information sequence.

In the RS part, the base sequence for generating the cyclically shiftedsequence may be identical to the base sequence of the information part.The CS index Ics of the information part and the CS index I′cs of the RSpart are both determined from the resource index. However, a method ofdetermining the CS index from the resource index may be identical ordifferent between the information part and the RS part.

FIG. 11 shows an example of PUCCH format 1/1a/1b transmission in case ofan extended CP. Although it is expressed herein that resource blocksbelonging to a resource block pair occupy the same frequency band in a1^(st) slot and a 2^(nd) slot, the resource blocks can be hopped in aslot level as described with reference to FIG. 7.

Referring to FIG. 11, the 1^(st) slot and the 2^(nd) slot each include 6OFDM symbols. Among the 6 OFDM symbols included in each slot, 2 OFDMsymbols correspond to an RS part, and the remaining 4 OFDM symbolscorrespond to an information part. Other than that, the example of FIG.10 in which the normal CP is used is applied directly. However, in theRS part, an RS sequence is generated on the basis of the cyclicallyshifted sequence and an orthogonal sequence having a length of K=2.

As described above, in both cases of the normal CP and the extended CP,a resource used for PUCCH format 1/1a/1b transmission has to beidentified by a resource index. A resource block for transmittinginformation, a CS index Ics and an orthogonal sequence index los forgeneration of an information sequence, and a CS index I′cs and anorthogonal sequence index I′os for generation of the RS sequence aredetermined from the resource index.

For example, when a CS interval is 2 in the extended CP, the UEmultiplexing capacity is as follows. Since the number of CS indices Icsand the number of orthogonal sequence indices los for the controlinformation are respectively 6 and 3, 18 UEs can be multiplexed per oneRB. However, the number of CS indices I′cs and the number of orthogonalsequence indices I′cs for generation of the RS sequence are respectively6 and 2, 12 UEs can be multiplexed per one resource block. Therefore,the UE multiplexing capacity is limited by the RS part rather than theinformation part.

FIG. 12 shows an example of PUCCH format 2 transmission when a normal CPis used. Although it is shown herein that resource blocks belonging to aresource block pair occupy the same frequency band in a 1^(st) slot anda 2^(nd) slot, the resource blocks may be hopped in a slot level asdescribed in FIG. 7.

Referring to FIG. 12, among the 7 OFDM symbols included in each slot, 2OFDM symbols correspond to an RS part to which an RS sequence is mapped,and the remaining 5 OFDM symbols correspond to an information part towhich an information sequence is mapped. The position and number of OFDMsymbols used as the RS part in each slot may vary, and thus the positionand number of OFDM symbols used as the information part may also vary.

A UE generates an encoded CQI bit by performing channel coding on a CQIinformation bit. In this case, a block code may be used. In 3GPP LTE, ablock code (20, A) is used, where A is a size of the CQI informationbit. That is, in the 3GPP LTE, encoded bits (20 bits) are generatedalways irrespective of the size of the CQI information bit.

Table 7 below shows an example of 13 basis sequences for the block code(20, A).

TABLE 7 i m(i, 0) M(i, 1) M(i, 2) M(i, 3) M(i, 4) M(i, 5) M(i, 6) M(i,7) M(i, 8) M(i, 9) M(i, 10) M(i, 11) M(i, 12) 0 1 1 0 0 0 0 0 0 0 0 1 10 1 1 1 1 0 0 0 0 0 0 1 1 1 0 2 1 0 0 1 0 0 1 0 1 1 1 1 1 3 1 0 1 1 0 00 0 1 0 1 1 1 4 1 1 1 1 0 0 0 1 0 0 1 1 1 5 1 1 0 0 1 0 1 1 1 0 1 1 1 61 0 1 0 1 0 1 0 1 1 1 1 1 7 1 0 0 1 1 0 0 1 1 0 1 1 1 8 1 1 0 1 1 0 0 10 1 1 1 1 9 1 0 1 1 1 0 1 0 0 1 1 1 1 10 1 0 1 0 0 1 1 1 0 1 1 1 1 11 11 1 0 0 1 1 0 1 0 1 1 1 12 1 0 0 1 0 1 0 1 1 1 1 1 1 13 1 1 0 1 0 1 0 10 1 1 1 1 14 1 0 0 0 1 1 0 1 0 0 1 0 1 15 1 1 0 0 1 1 1 1 0 1 1 0 1 16 11 1 0 1 1 1 0 0 1 0 1 1 17 1 0 0 1 1 1 0 0 1 0 0 1 1 18 1 1 0 1 1 1 1 10 0 0 0 0 19 1 0 0 0 0 1 1 0 0 0 0 0 0

In Table 7, M_(i,n) denotes a basis sequence (where 0≦n≦12, n is aninteger). The encoded bit is generated by linear combination of the 13basis sequences. Equation 7 below shows an example of the encoded bitb_(i) (0≦i≦19, where i is an integer).

$\begin{matrix}{{b(i)} = {\sum\limits_{n = 0}^{A - 1}{\left\{ {{a(n)} \cdot {M\left( {i,n} \right)}} \right\}{mod}\mspace{14mu} 2}}} & \left\lbrack {{Equation}\mspace{14mu} 7} \right\rbrack\end{matrix}$

In Equation 7, a₀, a₁, . . . , a_(A-1) denotes an information bit, and Adenotes the size of the information bit (where A is a natural number).

The encoded bits (20 bits) are mapped to 10 modulation symbols d(0), . .. , d(9) by using QPSK modulation. In the PUCCH format 2a, 1-bit HARQACK/NACK information is mapped to one modulation symbol d(10) by usingBPSK modulation. In the PUCCH format 2b, 2-bit HARQ ACK/NACK informationis mapped to one modulation symbol d(10) by using QPSK modulation. Thatis, in the PUCCH format 2a, the CQI and the 1-bit HARQ ACK/NACKinformation are concurrently transmitted, and in the PUCCH format 2b,the CQI and the 2-bit HARQ ACK/NACK information are concurrentlytransmitted. Herein, d(10) is used for generation of an RS. d(10)corresponds to one OFDM symbol between two OFDM symbols on which the RSis carried in each slot. In other words, according to d(10), phasemodulation is performed on the RS carried on one OFDM symbol in eachslot. The PUCCH formats 2a/2b can be supported only for the normal CP.As such, in each of the PUCCH formats 2a and 2b, one modulation symbolis used for generation of the RS.

In the information part, an information sequence is generated based onmodulation symbols d(0), . . . , d(9) and a cyclically shifted sequencer(n,Ics). Each modulation symbol can be multiplied to the cyclic shiftedsequence r(n,Ics). The information sequence is a one-dimensional spreadsequence. Unlike the PUCCH formats 1/1a/1b, an orthogonal sequence isnot used in the PUCCH formats 2/2a/2b.

The cyclically shifted sequence r(n,Ics) is generated from a basesequence for each OFDM symbol used as the information part within thesubframe. The base sequence is identical within one slot. The 1^(st)slot and the 2^(nd) slot may have identical or different base sequenceswithin the subframe. The cyclically shifted index Ics is determined froma resource index. The cyclically shifted index Ics can be CS-hopped in asymbol level. The CS hopping can be performed according to a slot numbern(s) within a radio frame and a symbol index I within a slot. Therefore,the CS index Ics can be expressed by Ics(n(s),I). In FIG. 13, a valueIcs for each OFDM symbol in the information part is for exemplarypurposes only.

In the RS part, the cyclically shifted sequence r(n,I′cs) can be used asthe RS sequence. I′cs is a CS index for the RS. I′cs is determined fromthe resource index.

In the RS part, the base sequence for generating the cyclically shiftedsequence may be identical to the base sequence of the information part.The CS index Ics of the information part and the CS index I′cs of the RSpart are both determined from the resource index. However, a method ofdetermining the CS index from the resource index may be identical ordifferent between the information part and the RS part.

In the PUCCH format 2a/2b, d(10) corresponds to one OFDM symbol of theRS part. That is, an RS sequence in which d(10) and the cyclicallyshifted sequence are multiplied is mapped to one OFDM symbol of the RSpart within each slot.

FIG. 13 shows an example of PUCCH format 2 transmission when an extendedCP is used. Although it is shown herein that resource blocks belongingto a resource block pair occupy the same frequency band in a 1^(st) slotand a 2^(nd) slot, the resource blocks may be hopped in a slot level asdescribed in FIG. 7.

Referring to FIG. 13, each of the 1^(st) slot and the 2^(nd) slotincludes 6 OFDM symbols. Among the 6 OFDM symbols included in each slot,one OFDM symbol corresponds to an RS part, and the remaining 5 OFDMsymbols correspond to an information part. Other than that, the normalCP case of FIG. 11 is applied directly.

As described above, in both cases of the normal CP and the extended CP,a resource used for PUCCH format 2/2a/2b transmission has to beidentified by a resource index. A resource block for transmittinginformation, a CS index Ics for generation of an information sequence,and a CS index I′cs for generation of an RS sequence are determined fromthe resource index. If a CS interval is 1, the number of CS indices Icsis 12 and the number of CS indices I′cs is 12. Thus, 12 UEs can bemultiplexed per one resource block. If the CS interval is 2, the numberof CS indices Ics is 6 and the number of CS indices I′cs is 6. Thus, 6UEs can be multiplexed per one resource block.

As such, information can be transmitted by using code divisionmultiplexing (CDM) and/or frequency division multiplexing (FDM) as amultiplexing scheme. Only one resource index is used in the informationtransmission method described up to now. However, to increase an amountof information that is transmitted concurrently, it may be necessary toallocate multiple resources to one UE. When allocating the multipleresources, there may be a problem in a method of transmitting a signalgenerated from information and a reference signal by using the multipleresources. Hereinafter, a method of transmitting a signal by usingmultiple resources will be described.

FIG. 14 is a block diagram showing an exemplary structure of atransmitter including two antennas. Herein, the transmitter may be apart of a UE or a part of a BS.

Referring to FIG. 14, a transmitter 200 includes an informationprocessor 210, a reference signal generator 220, 1^(st) and 2^(nd)resource block mappers 230-1 and 230-2, 1 ^(st) and 2^(nd) OFDM signalgenerators 240-1 and 240-2, 1^(st) and 2^(nd) RF units 250-1 and 250-2,and two antennas 290-1 and 290-2.

The 1^(st) and 2^(nd) resource block mappers 230-1 and 230-2 arerespectively coupled to the 1^(st) and 2^(nd) OFDM signal generators240-1 and 240-2. The 1^(st) and 2^(nd) OFDM signal generators 240-1 and240-2 are respectively coupled to the 1^(st) and 2^(nd) RF units 250-1and 250-2. The 1^(st) and 2^(nd) RF units 250-1 and 250-2 arerespectively coupled to the two antennas 290-1 and 290-2. That is, ann^(th) resource block mapper 230-n is coupled to an n^(th) OFDM symbolgenerator 240-n, the n^(th) OFDM signal generator 240-n is coupled to ann^(th) RF unit 250-n, and the n^(th) RF unit is coupled to an n^(th)antenna 290-n. In case of multiple-antenna transmission, there may beone resource grid defined for each antenna.

Two resource indices are allocated to the transmitter 200. Theinformation processor 210 generates information sequences based on thetwo resource indices. Other than that, the description on theinformation transmission method of FIG. 8 to FIG. 13 can also be appliedto a method and apparatus for information transmission through aplurality of Tx antennas.

Hereinafter, a method of generating information sequences based on tworesource indices in the information processor 210 will be described.

FIG. 15 is a block diagram showing an exemplary structure of a part of atransmitter including two antennas.

Referring to FIG. 15, the information processor 210 includes a channelcoding unit 211, a modulator 212, and 1^(st) and 2^(nd) informationsequence generators 213-1 and 213-2. The 1^(st) information sequencegenerator 213-1 is coupled to a 1^(st) resource block mapper 230-1, andthe 2^(nd) information sequence generator 213-2 is coupled to a 2^(nd)resource block mapper 230-2.

The information processor 210 can generate information sequences byusing orthogonal space resource transmit diversity (OSRTD) or orthogonalspace resource spatial multiplexing (OSRSM).

1. OSRTD

It is assumed that s(1) is a complex-valued signal corresponding toinformation to be transmitted by the transmitter 200. Herein, thecomplex-valued signal may be any signal, one or more modulation symbols,or a spread sequence.

The modulator 212 outputs s(1). Then, s(1) is input to each of the1^(st) information sequence generator 213-1 and the 2^(nd) informationsequence generator 213-2.

The 1^(st) information sequence generator 213-1 generates a 1^(st)information sequence based on s(1) and a 1^(st) resource index. The2^(nd) information sequence generator 213-2 generates a 2^(nd)information sequence based on s(1) and a 2^(nd) resource index. The1^(st) information sequence is transmitted through the 1^(st) antenna290-1, and the 2^(nd) information sequence is transmitted through the2^(nd) antenna 290-2. When the 1^(st) resource index and the 2^(nd)resource index are allocated differently, orthogonality can bemaintained between antennas.

In order to perform channel estimation for each antenna, an RS has to begenerated for each antenna. For this, each resource index may be mappedto each antenna in a one-to-one manner. Therefore, an RS for the 1^(st)antenna may be generated based on the 1^(st) resource index, and an RSfor the 2^(nd) antenna may be generated based on the 2^(nd) resourceindex.

As such, the OSRTD is a method in which a resource index is allocatedfor each antenna and the same information is repetitively transmitted inan orthogonal manner for each antenna. By repetitively transmitting thesame information through a plurality of antennas, a diversity gain canbe obtained, and reliability of wireless communication can be increased.

If it is assumed that 18 UEs can be multiplexed per one resource blockin case of single-antenna transmission, 9 UEs can be multiplexed per oneresource block when using OSRTD for two antennas. In case of the PUCCHformat 1/1a/1b, the same information is transmitted in a 1^(st) slot anda 2^(nd) slot. A resource block allocated to the PUCCH is hopped in aslot level. That is, by transmitting information through differentsubcarriers over time, a frequency diversity gain can be obtained.However, if a sufficient diversity gain can be obtained by using theOSRTD, the same control information as that of the 1^(st) slot is notnecessarily transmitted in the 1^(st) slot. Therefore, differentinformation can be transmitted in the 1^(st) slot and the 2^(nd) slot.In this case, UE multiplexing capacity of the OSRTD for the two antennasmay be maintained to be the same as UE multiplexing capacity ofsingle-antenna transmission. For example, in case of the single-antennatransmission, if 18 UEs are multiplexed per one resource block, 18 UEscan also be multiplexed per one resource block even in the OSRTD for thetwo antennas.

The 2^(nd) information sequence generator 213-2 may generate the 2^(nd)information sequence by modifying the complex-valued signal s(1). Forexample, the 2^(nd) information sequence can be generated based on s(1)*and the 2^(nd) resource index. Herein, (•)* denotes a complex conjugate.Alternately, a modified complex-valued signal s(2) processed by the2^(nd) information sequence generator can be expressed by Equation 8below.s(2)=s(1)−exp(jθ) or a−s(1)  [Equation 8]

In Equation 8, ‘a’ denotes a complex-valued scaling factor of the 2^(nd)information sequence generator.

A Tx signal matrix can be expressed by Equation 9 below.

$\begin{matrix}\begin{bmatrix}{s(1)} & 0 \\0 & {s(1)}\end{bmatrix} & \left\lbrack {{Equation}\mspace{14mu} 9} \right\rbrack\end{matrix}$

In Equation 9, a row and/or column of the Tx signal matrix maycorrespond to a Tx antenna, a resource index, etc. For example, rows ofthe Tx signal matrix may correspond to respective resource indices, andcolumns thereof may correspond to respective Tx antennas.

y(1) denotes a 1^(st) Rx signal for the 1^(st) information sequencegenerated based on the 1^(st) resource index. y(2) denotes a 2^(nd) Rxsignal for the 2^(nd) information sequence generated based on the 2^(nd)resource index. An actual Rx signal y is a combination of the 1^(st) Rxsignal y1 and the 2^(nd) Rx signal y2, i.e., y=y(1)+y(2). However, it isassumed that the Rx signal y can be split into the 1^(st) Rx signal y1and the 2^(nd) Rx signal y2 by using a de-spreading operation. Forconvenience of explanation, it is assumed that a receiver has one Rxantenna.

An Rx signal matrix can be expressed by Equation 10 below.

$\begin{matrix}{\begin{bmatrix}{y(1)} \\{y(2)}\end{bmatrix} = {{\begin{bmatrix}{s(1)} & 0 \\0 & {s(1)}\end{bmatrix}\begin{bmatrix}{h(1)} \\{h(2)}\end{bmatrix}} + \begin{bmatrix}{n(1)} \\{n(2)}\end{bmatrix}}} & \left\lbrack {{Equation}\mspace{14mu} 10} \right\rbrack\end{matrix}$

In Equation 10, h(1) denotes a channel for the 1^(st) antenna 290-1,h(2) denotes a channel for the 2^(nd) antenna 290-1, n(1) denotes noiseof the 1^(st) Rx signal, and n(2) denotes noise of the 2^(nd) Rx signal.Herein, the noise may be additive white Gaussian noise (AWGN).

In general, if Tx power is limited, a normalization factor correspondingto the number of Tx antennas can be used. Equation 11 below shows anexample of the normalization factor.

$\begin{matrix}\frac{1}{\sqrt{{Ntx} \times {Nc}}} & \left\lbrack {{Equation}\mspace{14mu} 11} \right\rbrack\end{matrix}$

In Equation 11, Ntx denotes the number of Tx antennas, and Nc denotesthe number of resources per antenna. However, for convenience ofexplanation, the normalization factor is omitted in the followingdescription.

When de-spreading is performed on each resource index from the Rxsignal, a diversity gain can be obtained as expressed by Equation 12below.|h(1)|² +|h(2)|²  [Equation 12]

The diversity gain is similar to maximal ratio coding (MRC) which isoptimal combining. The MRC scheme is one of signal combining schemes forestimating a Tx signal from an Rx signal received through a plurality ofRx antennas.

Although it is described herein that the number of Tx antennas is 2 forconvenience of explanation, the number of Tx antennas is not limitedthereto.

When the transmitter includes M antennas (where M is a natural number),M resource indices can be allocated. The M antennas can be one-to-onemapped to the M resource indices, respectively. If the number of Txantennas is 3 or more, OSRTD can be used in combination with other Txdiversity schemes such as cyclic delay diversity (CDD) or precodingvector switching (PVS). For example, when using 4 Tx antennas, the 4Txantennas can be divided by two, and thus can be grouped into two antennagroups. The OSRTD is applied to each of the two antenna groups, and theCDD or the PVS can be applied between the groups.

2. OSRSM

It is assumed that s(1) and s(2) are complex-valued signalscorresponding to information to be transmitted by the transmitter 200.

The 1^(st) information sequence generator 213-1 generates the 1^(st)information sequence based on the 1^(st) information symbols s(1) andthe 1^(st) resource index. The 2^(nd) information sequence generator213-2 generates the 2^(nd) information sequence based on the 2^(nd)information symbol s(2) and the 2^(nd) resource index. The 1^(st)information sequence is transmitted through the 1^(st) antenna 290-1,and the 2^(nd) information sequence is transmitted through the 2^(nd)antenna 290-2. When the 1^(st) resource index and the 2^(nd) resourceindex are allocated differently, orthogonality can be maintained betweenantennas.

In order to perform channel estimation for each antenna, an RS has to begenerated for each antenna. For this, each resource index may be mappedto each antenna in a one-to-one manner. Therefore, an RS for the 1^(st)antenna may be generated based on the 1^(st) resource index, and an RSfor the 2^(nd) antenna may be generated based on the 2^(nd) resourceindex.

Although it is described herein that the number of Tx antennas is 2 forconvenience of explanation, the number of Tx antennas is not limitedthereto.

When the transmitter includes M antennas (where M is a natural number),the transmitter can transmit M symbols. M resource indices can beallocated to the transmitter. The M antennas can be one-to-one mapped tothe M resource indices, respectively. Different symbols can betransmitted through the respective M antennas. As such, an informationtransmission method having a spatial multiplexing rate of M is calledOSRSM.

The encoded bit which is bit-level information output from the channelcoding unit 211 can be permutated before being modulated by themodulator 212.

It is assumed that 1^(st) encoded bits (2 bits) a(0) and a(1) and 2^(nd)encoded bits (2 bits) b(0) and b(1) are input to the modulator 212. Forexample, the 1^(st) encoded bit may be bit-level information of 1^(st)ACK/NACK for 1^(st) data transmitted through a 1^(st) DL carrier, andthe 2^(nd) encoded bit may be bit-level information of 2^(nd) ACK/NACKfor 2^(nd) data transmitted through a 2^(nd) DL carrier.

The modulator 212 may generate a 1^(st) modulation symbol d(0) byperforming QPSK modulation on the 1^(st) encoded bit, and may generate a2^(nd) modulation symbol e(0) by performing QPSK modulation on the2^(nd) encoded bit.

Alternatively, the modulator 212 may replace the 1^(st) encoded bit andthe 2^(nd) encoded bit and then modulate the bits after replacement. Forexample, the modulator 212 may replace the bits by swapping the 1^(st)bits a(0) and b(0) of the 1^(st) and 2^(nd) encoded bits. The modulatormay generate the 1^(st) modulation symbol d(0) by modulating the bitsb(0) and a(1), and may generate the 2^(nd) modulation symbol e(0) bymodulating the bits a(0) and b(1).

The modulation symbols output from the modulator 212 are input to asplitter (not shown). The splitter splits the modulation symbol into the1^(st) information symbol s(1) and the 2^(nd) information symbol s(2) byusing the 1^(st) modulation symbol d(0) and the 2^(nd) modulation symbole(0). For one example, the 1^(st) modulation symbol may correspond tothe 1^(st) information symbol, and the 2^(nd) modulation symbol maycorrespond to the 2^(nd) information symbol. For another example, the1^(st) modulation symbol and the 2^(nd) modulation symbol may bereplaced and/or mixed and then may be split into the 1^(st) informationsymbol and the 2^(nd) information symbol.

Equation 13 below shows examples of the 1^(st) modulation symbol d(0)and the 2^(nd) modulation symbol e(0) which are replaced and/or mixedand then are split into the 1^(st) information symbol s(1) and the2^(nd) information symbol s(2).s(1)=d(0)+e(0), s(2)=d(0)−e(0)s(1)=d(0)−e(0), s(2)=e(0)−d(0)*  [Equation 13]

Alternatively, as expressed by Equation 14 below, the 1^(st) modulationsymbol d(0) and the 2^(nd) modulation symbol e(0) may be rotated by anyphase, be replaced and/or mixed, and then be split into the 1^(st)information symbol s(1) and the 2^(nd) information symbol s(2).s(1)=d(0)+e(0)e ^(ja) , s(2)=d(0)−e(0)e ^(jb)s(1)=d(0)−e(0)*e ^(ja) , s(2)=e(0)+d(0)*e ^(jb)

In Equation 14, ‘a’ and ‘b’ may be identical or different from eachother.

In both of the OSRTD and OSRSM schemes, a plurality of antennas can bemapped to a plurality of resource indices in a one-to-one manner.Therefore, one resource index is used for each antenna to generate andtransmit an information sequence and an RS sequence.

FIG. 16 is a block diagram showing an exemplary structure of a part of atransmitter including a single antenna. Herein, the transmitter may bethe transmitter 100 of FIG. 8.

Referring to FIG. 16, an information processor 110 includes a channelcoding unit 111, a modulator 112, and 1^(st) and 2^(nd) informationsequence generators 113-1 and 113-2. The 1^(st) and 2^(nd) informationsequence generators 113-1 and 113-2 are coupled to a resource blockmapper 130.

The modulator 112 outputs a 1^(st) complex-valued signal s(1) and a2^(nd) complex-valued signal s(2). Each of the signals s(1) and s(2) isa complex-valued signal corresponding to information to be transmittedby the transmitter 100. Herein, the complex-valued signal may be anysignal, one or more modulation symbols, or a spread sequence.

The 1^(st) complex-valued signal may correspond to 1^(st) informationfor a 1^(st) DL carrier. The 2^(nd) complex-valued signal may correspondto 2^(nd) information for a 2^(nd) DL carrier. The 1^(st) informationand the 2^(nd) information may be transmitted through the same carrier.The 1^(st) information may be 1^(st) ACK/NACK for 1^(st) data receivedby the UE through the 1^(st) DL carrier. The 2^(nd) information may be2^(nd) ACK/NACK for 2^(nd) data received by the UE through the 2^(nd) DLcarrier. Alternatively, the 1^(st) information may be 1^(st) CQI for the1^(st) DL carrier, and the 2^(nd) information may be 2^(nd) CQI for the2^(nd) DL carrier. That is, a 1^(st) resource index may be allocated tothe 1^(st) DL carrier, and a 2^(nd) resource index may be allocated tothe 2^(nd) DL carrier. In this case, information for each of the 1^(st)DL carrier and the 2^(nd) DL carrier may be transmitted through one ULcarrier. Therefore, the transmitter of FIG. 14 can be used in anasymmetric multi-carrier system in which the number of DL carriers isgreater than the number of UL carriers. For example, it may be used in amulti-carrier system in which the ratio of the number of DL carriers tothe number UL carriers is 2:1.

Alternatively, each of the 1^(st) information and the 2^(nd) informationmay be representative information. The representative information is onepiece of information representing a plurality of pieces of information.Representing the plurality of pieces of information into one piece ofrepresentative information is called information bundling. Examples ofthe representative information include representative CQI,representative ACK/NACK, representative PMI, etc. The representative CQImay be one CQI for a plurality of DL carriers. For example, therepresentative CQI may be an average CQI for respective CQIs for aplurality of DL carriers. Alternatively, the representative CQI may beone CQI representing the respective CQIs for a plurality of codewords.The representative ACK/NACK may be one HARQ ACK/NACK for each datatransmitted through the plurality of DL carriers. For example, ifdecoding of each data transmitted through the plurality of DL carriersis completely successful, the representative ACK/NACK is ACK, andotherwise the representative ACK/NACK is NACK. Alternatively, therepresentative ACK/NACK may be one HARQ ACK/NACK representing eachACK/NACK for a plurality of codewords.

For one example, the 1^(st) information may be 1^(st) representativeinformation for a 1^(st) DL carrier and a 2^(nd) DL carrier, and the2^(nd) information may be 2^(nd) representative information for a 3^(rd)DL carrier and a 4^(th) DL carrier. For another example, the 1^(st)information may be 1^(st) representative information for a plurality ofcodewords, and the 2^(nd) information may be 2^(nd) representativeinformation for other codewords.

The 1^(st) complex-valued signal s(1) is input to the 1^(st) informationsequence generator 113-1, and the 2^(nd) complex-valued signal s(2) isinput to the 2^(nd) information sequence generator 113-2.

The 1^(st) information sequence generator 113-1 generates a 1^(st)information sequence based on the s(1) and a 1^(st) resource index. The2^(nd) information sequence generator 113-2 generates a 2^(nd)information sequence based on the s(2) and a 2^(nd) resource index.

Each of the 1^(st) information sequence and the 2^(nd) informationsequence is input to the resource block mapper 130. In this case, the1^(st) information sequence and/or the 2^(nd) information sequence maybe subjected to phase shift. This is to prevent the 1^(st) informationsequence and the 2^(nd) information sequence from being offset when thetwo sequences are combined.

A 1^(st) resource block (RB) is determined from the 1^(st) resourceindex, and a 2^(nd) RB is determined from the 2^(nd) resource index. Inthis case, the 1^(st) RB and the 2^(nd) RB may be identical to eachother or different from each other.

FIG. 17 shows another example of a case where a 1^(st) RB is differentfrom a 2^(nd) RB.

Referring to FIG. 17, a resource block mapper 130 maps a 1^(st)information sequence to an information part of the 1^(st) RB, and maps a2^(nd) information sequence to an information part of the 2^(nd) RB.

In this case, an RS sequence mapped to an RS part of the 1^(st) RB isgenerated based on a 1^(st) resource index. An RS sequence mapped to anRS part of the 2^(nd) RB is generated based on a 2^(nd) resource index.

If the 1^(st) RB indicated by the 1^(st) resource index is differentfrom the 2^(nd) RB indicated by the 2^(nd) resource index, aninformation sequence and an RS sequence are both generated based on thetwo resource indices.

FIG. 18 shows an example in which a 1^(st) RB is identical to a 2^(nd)RB.

Referring to FIG. 18, a resource block mapper 130 adds a 1^(st)information sequence and a 2^(nd) information sequence and maps theadded sequences to an information part of the RBs. In this case, the1^(st) information sequence and the 2^(nd) information sequence may beadded, or the 1^(st) information sequence and/or the 2^(nd) informationsequence may be subjected to phase shift and then be added.

An RS sequence mapped to an RS part of an RB is generated based on oneresource index among a 1^(st) resource index and a 2^(nd) resourceindex. Since channel estimation is possible by using only the RSsequence generated based on one resource index among the two resourceindices, the RS sequence shall be generated based on one of the tworesource indices.

There is no particular restriction on a resource index based on whichthe RS sequence is generated between the 1^(st) resource index and the2^(nd) resource index. However, a receiver has to know the resourceindex based on which the RS sequence is generated for channelestimation. Therefore, a method of selecting a resource index forgenerating the RS sequence may be determined in advance by a protocol.For example, the RS sequence may be generated based on a smallerresource index between the two resource indices. Alternatively, theresource index based on which the RS sequence is generated may bereported through signaling.

As such, if the 1^(st) RB indicated by the 1^(st) resource index isidentical to the 2^(nd) RB indicated by the 2^(nd) resource index, twoinformation sequences are generated based on the two resource indices,whereas the RS sequence is generated based on one of the two resourceindices.

FIG. 19 is a block diagram showing another exemplary structure of a partof a transmitter including two antennas.

Referring to FIG. 19, an information processor 210 includes a channelcoding unit 211, a modulator 212, and a space-code block code (SCBC)processor 214. The SCBC processor 214 is coupled to 1^(st) and 2^(nd)resource mappers 230-1 and 230-2.

It is assumed that a 1^(st) complex-valued signal s(1) and a 2^(nd)complex-valued signal s(2) are complex-valued signals corresponding toinformation to be transmitted by the transmitter 200.

The SCBC processor 214 generates a 1^(st) Tx vector and a 2^(nd) Txvector based on an Alamouti code from the 1^(st) complex-valued signals(1) and the 2^(nd) complex-valued signal s(2). The 1^(st) Tx vector istransmitted through the 1^(st) antenna 290-1, and the 2^(nd) Tx vectoris transmitted through the 2^(nd) antenna 290-2.

The 1^(st) Tx vector consists of a 1^(st) Tx symbol and a 2^(nd) Txsymbol. The 2^(nd) Tx vector consists of a 3^(rd) Tx symbol and a 4^(th)Tx symbol.

(1) 1^(st) Tx Vector

A 1^(st) information sequence is generated based on the 1^(st) Tx symboland a 1^(st) resource index.

A 2^(nd) information sequence is generated based on the 2^(nd) Tx symboland a 2^(nd) resource index.

The 1^(st) information sequence and the 2^(nd) information sequence areinput to the 1^(st) resource block mapper 230-1.

(2) 2^(nd) Tx Vector

A 3^(rd) information sequence is generated based on the 3^(rd) Tx symboland the 1^(st) resource index.

A 4^(th) information sequence is generated based on the 4^(th) Tx symboland the 2^(nd) resource index.

The 3^(rd) information sequence and the 4^(th) information sequence areinput to the 2^(nd) resource block mapper 230-2.

Therefore, the 1^(st) information sequence and the 2^(nd) informationsequence may be combined and transmitted through the 1^(st) antenna. The2^(nd) information sequence and the 4^(th) information sequence may becombined and transmitted through the 2^(nd) antenna. To decrease a cubicmetric (CM), a phase of at least one information sequence may changewhen combining one information sequence to another information sequence.Alternatively, a phase of a Tx symbol may change before the informationsequence is generated. For example, the 2^(nd) information sequence maybe added to the 1^(st) information sequence by phase-shifting the 2^(nd)information sequence by a specific phase. In addition, the 4^(th)information sequence may be added to the 3^(rd) information sequence byphase-shifting the 4^(th) information sequence by a specific phase. Incase of BPSK, the specific phase may be 90 degrees. In case of QPSK, thespecific phase may be 45 degrees.

As such, when CDM/FDM is used as a multiplexing scheme, information canbe transmitted by using a resource according to SCBC. The transmittercan perform smart repetition by using an antenna and a resource, therebybeing able to obtain a diversity gain and to increase reliability ofwireless communication. Hereinafter, such an information transmissionmethod is called an SCBC information transmission method.

In the SCBC information transmission method, a resource index allocatedto an information part is not mapped to an antenna in a one-to-onemanner. However, an RS has to be generated for each antenna in order toperform channel estimation for each antenna. For this, each resourceindex can be mapped to each antenna in a one-to-one manner. Therefore,an RS for the 1^(st) antenna can be generated based on the 1^(st)resource index, and an RS for the 2^(nd) antenna can be generated basedon the 2^(nd) resource index.

For SCBC information transmission, it is described above that the 2^(nd)resource index is further allocated to the transmitter in addition tothe 1^(st) resource index. However, if different information has alreadybeen allocated by using a different resource index, the 2^(nd) resourceindex is not necessarily allocated additionally.

If it is assumed that 18 UEs can be multiplexed per one resource blockin case of single-antenna transmission, 9 UEs can be multiplexed per oneresource block when applying an SCBC transmission method using twoantennas. In case of the PUCCH format 1/1a/1b, the same information istransmitted in a 1^(st) slot and a 2^(nd) slot. A resource blockallocated to the PUCCH is hopped in a slot level. That is, bytransmitting information through different subcarriers over time, afrequency diversity gain can be obtained. However, if a sufficientdiversity gain can be obtained by using the SCBC transmission method,the same control information as that of the 1^(st) slot is notnecessarily transmitted in the 2^(nd) slot. Therefore, differentinformation can be transmitted in the 1^(st) slot and the 2^(nd) slot.In this case, UE multiplexing capacity of the SCBC transmission methodfor the two antennas may be maintained to be the same as UE multiplexingcapacity of single-antenna transmission. For example, in case of thesingle-antenna transmission, if 18 UEs are multiplexed per one resourceblock, 18 UEs can also be multiplexed per one resource block even in theSCBC transmission method for the two antennas.

Hereinafter, a Tx signal matrix is defined as a 2×2 matrix of which a1^(st) column is the 1^(st) Tx vector and a 2^(nd) column is the 2^(nd)Tx vector. An element of an i^(th) row and a j^(th) column of the Txmatrix is expressed by (i,j) (where i=1, 2 and j=1, 2). (1,1) and (2,1)respectively denote the 1^(st) Tx symbol and the 2^(nd) Tx symbol of the1^(st) Tx vector. (1,2) and (2,2) respectively denote the 3^(rd) Txsymbol and the 4^(th) Tx symbol of the 2^(nd) Tx vector.

A Tx signal matrix can be expressed by Equation 15 below.

$\begin{matrix}\begin{bmatrix}{s(1)} & {s(2)} \\{- {s(2)}^{*}} & {s(1)}^{*}\end{bmatrix} & \left\lbrack {{Equation}\mspace{14mu} 15} \right\rbrack\end{matrix}$

In Equation 15, a row and/or column of the Tx signal matrix maycorrespond to a Tx antenna, a resource index, etc. For example, rows ofthe Tx signal matrix may correspond to respective resource indices, andcolumns thereof may correspond to respective Tx antennas.

The Tx signal matrix expressed in Equation 15 above is for exemplarypurposes only, and is not for restricting a format of the Tx signalmatrix. The Tx signal matrix includes all possible unitary transforms ofthe matrix of Equation 15 above. In this case, the unitary transformincludes not only a transform for the 1^(st) information symbol s(1) andthe 2^(nd) information symbol s(2) but also a transform in a state wheres(1) and s(2) are separated into a real part and an imaginary part.

y(1) denotes a 1^(st) Rx signal for the 1^(st) information sequencegenerated based on the 1^(st) resource index. y(2) denotes a 2^(nd) Rxsignal for the 2^(nd) information sequence generated based on the 2^(nd)resource index. An actual Rx signal y is a combination of the 1^(st) Rxsignal y1 and the 2^(nd) Rx signal y2, i.e., y=y(1)+y(2). However, it isassumed that the Rx signal y can be split into the 1^(st) Rx signal y1and the 2^(nd) Rx signal y2 by using a de-spreading operation. Forconvenience of explanation, it is assumed that a receiver has one Rxantenna.

An Rx signal matrix can be expressed by Equation 16 below.

$\begin{matrix}{\begin{bmatrix}{y(1)} \\{y(2)}\end{bmatrix} = {{\begin{bmatrix}{s(1)} & {s(2)} \\{- {s(2)}^{*}} & {s(1)}^{*}\end{bmatrix}\begin{bmatrix}{h(1)} \\{h(2)}\end{bmatrix}} + \begin{bmatrix}{n(1)} \\{n(2)}\end{bmatrix}}} & \left\lbrack {{Equation}\mspace{14mu} 16} \right\rbrack\end{matrix}$

In Equation 16, h(1) denotes a channel for the 1^(st) antenna 290-1,h(2) denotes a channel for the 2^(nd) antenna 290-1, n(1) denotes noiseof the 1^(st) Rx signal, and n(2) denotes noise of the 2^(nd) Rx signal.Herein, the noise may be AWGN.

In general, if Tx power is limited, a normalization factor correspondingto the number of Tx antennas can be used. For convenience ofexplanation, the normalization factor is omitted in the followingdescription.

Equation 16 above can be equivalently expressed by Equation 17 below.

$\begin{matrix}{\begin{bmatrix}{y(1)} \\{y(2)}^{*}\end{bmatrix} = {{\begin{bmatrix}{h(1)} & {h(2)} \\{h(2)}^{*} & {- {h(1)}^{*}}\end{bmatrix}\begin{bmatrix}{s(1)} \\{s(2)}\end{bmatrix}} + \begin{bmatrix}{n(1)} \\{n(2)}^{*}\end{bmatrix}}} & \left\lbrack {{Equation}\mspace{14mu} 17} \right\rbrack\end{matrix}$

Equation 17 above can be modified to Equation 18 below.

$\begin{matrix}{{\begin{bmatrix}{h(1)} & {h(2)} \\{h(2)}^{*} & {- {h(1)}^{*}}\end{bmatrix}^{H}\begin{bmatrix}{y(1)} \\{y(2)}^{*}\end{bmatrix}} = {{{\begin{bmatrix}{h(1)} & {h(2)} \\{h(2)}^{*} & {- {h(1)}^{*}}\end{bmatrix}^{H}\begin{bmatrix}{h(1)} & {h(2)} \\{h(2)}^{*} & {- {h(1)}^{*}}\end{bmatrix}}\begin{bmatrix}{s(1)} \\{s(2)}\end{bmatrix}} + {\begin{bmatrix}{h(1)} & {h(2)} \\{h(2)}^{*} & {- {h(1)}^{*}}\end{bmatrix}^{H}{\quad{\begin{bmatrix}{n(1)} \\{n(2)}^{*}\end{bmatrix} = {\begin{bmatrix}{{{h(1)}}^{2} + {{h(2)}}^{2}} & 0 \\0 & {{{h(1)}^{2} + {{h(2)}}^{2}}}\end{bmatrix}{\quad{\begin{bmatrix}{s(1)} \\{s(2)}\end{bmatrix} + \begin{bmatrix}{n^{\prime}(1)} \\{n^{\prime}(2)}\end{bmatrix}}}}}}}}} & \left\lbrack {{Equation}\mspace{14mu} 18} \right\rbrack\end{matrix}$

In Equation 18, (•)^(H) denotes a Hermitian matrix. The 1^(st) symbol s₁and the 2^(nd) symbol s₂ are orthogonally separated. The receiver canobtain a diversity gain expressed by Equation 12. This is the samediversity gain as the MRC which is the optimal combination.

Although it is described herein that the number of Tx antennas is 2 forconvenience of explanation, the number of Tx antennas is not limitedthereto.

When the transmitter includes M antennas (where M is a natural number),M resource indices can be allocated. The M antennas can be one-to-onemapped to the M resource indices, respectively. If the number of Txantennas is 3 or more, the SCBC information transmission method can beused in combination with other Tx diversity schemes such as cyclic delaydiversity (CDD) or precoding vector switching (PVS). For example, whenusing 4 Tx antennas, the 4Tx antennas can be divided by two, and thuscan be grouped into two antenna groups. The SCBC informationtransmission method is applied to each of the two antenna groups, andthe CDD or the PVS can be applied between the groups.

The transmitter of FIG. 16 and the transmitter of FIG. 19 have a commonpoint in that two resource indices are allocated per antenna for aninformation part. That is, in the information part, an antenna and aresource index are not mapped in a one-to-one manner. However, in an RSpart, the antenna and the resource index can be mapped in a one-to-onemanner so that channel estimation is possible for each antenna.Therefore, if a plurality of resource indices is allocated to oneantenna, an RS for an antenna may be generated in a different mannerfrom generation of an information sequence.

The information transmission method described up to now is applicable toall CDM/FDM-type information transmission methods based on PUCCH format1/1a/1b, format 2/2a/2b, etc.

FIG. 20 is a block diagram showing wireless communication system toimplement an embodiment of the present invention. A BS 50 may include aprocessor 51, a memory 52 and a radio frequency (RF) unit 53. Theprocessor 51 may be configured to implement proposed functions,procedures and/or methods described in this description. Layers of theradio interface protocol may be implemented in the processor 51. Thememory 52 is operatively coupled with the processor 51 and stores avariety of information to operate the processor 51. The RF unit 53 isoperatively coupled with the processor 11, and transmits and/or receivesa radio signal. A UE 60 may include a processor 61, a memory 62 and a RFunit 63. The processor 61 may be configured to implement proposedfunctions, procedures and/or methods described in this description.Layers of the radio interface protocol may be implemented in theprocessor 51. The memory 62 is operatively coupled with the processor 61and stores a variety of information to operate the processor 61. The RFunit 63 is operatively coupled with the processor 61, and transmitsand/or receives a radio signal.

The processors 51, 61 may include application-specific integratedcircuit (ASIC), other chipset, logic circuit and/or data processingdevice. The memories 52, 62 may include read-only memory (ROM), randomaccess memory (RAM), flash memory, memory card, storage medium and/orother storage device. The RF units 53, 63 may include baseband circuitryto process radio frequency signals. When the embodiments are implementedin software, the techniques described herein can be implemented withmodules (e.g., procedures, functions, and so on) that perform thefunctions described herein. The modules can be stored in memories 52, 62and executed by processors 51, 61. The memories 52, 62 can beimplemented within the processors 51, 61 or external to the processors51, 61 in which case those can be communicatively coupled to theprocessors 51, 61 via various means as is known in the art.

As such, a method and apparatus for effective signal transmission in awireless communication system can be provided. When multiple resourcesare allocated, an ambiguity problem of an information sequencegeneration method and a reference signal sequence generation method canbe solved by using the multiple resources. Accordingly, reliability ofwireless communication can be increased, and overall system performancecan be improved.

Additional advantages, objectives, and features of the present inventionwill become more apparent to those of ordinary skill in the art uponimplementation of the present invention based on the aforementioneddescriptions or explanation. Moreover, other unexpected advantages maybe found as those ordinary skilled in the art implement the presentinvention based on the aforementioned explanations.

Although a series of steps or blocks of a flowchart are described in aparticular order when performing methods in the aforementioned exemplarysystem, the steps of the present invention are not limited thereto.Thus, some of these steps may be performed in a different order or maybe concurrently performed. Those skilled in the art will understand thatthese steps of the flowchart are not exclusive, and that another stepcan be included therein or one or more steps can be omitted withouthaving an effect on the scope of the present invention.

Various modifications may be made in the aforementioned embodiments.Although all possible combinations of the various modifications of theembodiments cannot be described, those ordinary skilled in that art willunderstand possibility of other combinations. For example, thoseordinary skilled in the art will be able to implement the invention bycombining respective structures described in the aforementionedembodiments. Therefore, the present invention is not intended to belimited to the embodiments shown herein but is to be accorded the widestscope consistent with the principles and novel features disclosedherein.

What is claimed is:
 1. A method for receiving, by a base station,control information, in a wireless communication system, the methodcomprising: transmitting information on a first resource index for afirst antenna and a second resource index for a second antenna, whereinthe first resource index indicates a first resource block, and whereinthe second resource index indicates a second resource block which isdifferent from the first resource block; receiving first controlinformation through the first antenna and second control informationthrough the second antenna in a subframe; and receiving a firstreference signal through the first antenna and a second reference signalthrough the second antenna in the subframe, wherein the first controlinformation and the first reference signal are generated based on thefirst resource index, wherein the second control information and thesecond reference signal are generated based on the second resourceindex, and wherein the first control information and the second controlinformation is received via a physical uplink control channel (PUCCH).2. The method of claim 1, wherein the first control information ismapped to an information part of the first resource block, and the firstreference signal is mapped to a reference signal part of the firstresource block, and wherein the second control information is mapped toan information part of the second resource block, and the secondreference signal is mapped to a reference signal part of the secondresource block.
 3. The method of claim 1, wherein a resource blockindicated by a resource index includes M orthogonal frequency divisionmultiplexing (OFDM) symbols (where M is a natural number greater than orequal to 2), wherein N OFDM symbols out of the M OFDM symbols correspondto an information part to which control information is mapped, where Nis an integer, and wherein the remaining (M−N) OFDM symbols correspondto a reference signal part to which a reference signal is mapped.
 4. Themethod of claim 1, wherein a sequence and a resource block aredetermined from a resource index, wherein a spread information sequenceis generated based on information and the sequence, and wherein thespread information sequence is mapped to the resource block.
 5. Themethod of claim 4, wherein the sequence is a cyclically shiftedsequence.
 6. The method of claim 1, wherein a first sequence, a secondsequence, and a resource block are determined from a resource index,wherein a two-dimensional spread information sequence is generated basedon information, the first sequence and the second sequence, and whereinthe two-dimensional spread information sequence is mapped to theresource block.
 7. The method of claim 6, wherein the first sequence isa cyclically shifted shift, and wherein the second sequence is anorthogonal sequence.
 8. The method of claim 1, wherein the PUCCH usesone of PUCCH format 1/1a/1b, PUCCH format 2/2a/2b or PUCCH format
 3. 9.The method of claim 1, wherein the first resource index furtherindicates a first cyclic shift (CS), and wherein the second resourceindex further indicates a second CS.
 10. The method of claim 9, whereinthe first CS and the second CS are different from each other oridentical.
 11. The method of claim 1, wherein the first resource indexfurther indicates a first orthogonal code (OC), and wherein the secondresource index further indicates a second OC.
 12. The method of claim11, wherein the first OC and the second OC are different from each otheror identical.
 13. A base station in a wireless communication system, thebase station comprising: a radio frequency (RF) unit for transmitting orreceiving a radio signal; and a processor coupled to the RF unit, andconfigured to: transmit information on a first resource index for afirst antenna and a second resource index for a second antenna, whereinthe first resource index indicates a first resource block, and whereinthe second resource index indicates a second resource block which isdifferent from the first resource block; receive first controlinformation through the first antenna and second control informationthrough the second antenna in a subframe; and receive a first referencesignal through the first antenna and a second reference signal throughthe second antenna in the subframe, wherein the first controlinformation and the first reference signal are generated based on thefirst resource index, wherein the second control information and thesecond reference signal are generated based on the second resourceindex, and wherein the first control information and the second controlinformation is received via a physical uplink control channel (PUCCH).14. The base station of claim 13, wherein the first control informationis mapped to an information part of the first resource block, and thefirst reference signal is mapped to a reference signal part of the firstresource block, and wherein the second control information is mapped toan information part of the second resource block, and the secondreference signal is mapped to a reference signal part of the secondresource block.
 15. The base station of claim 13, wherein a resourceblock indicated by a resource index includes M orthogonal frequencydivision multiplexing (OFDM) symbols (where M is a natural numbergreater than or equal to 2), wherein N OFDM symbols out of the M OFDMsymbols correspond to an information part to which control informationis mapped, where N is an integer and wherein the remaining (M−N) OFDMsymbols correspond to a reference signal part to which a referencesignal is mapped.
 16. The base station of claim 13, wherein a sequenceand a resource block are determined from a resource index, wherein aspread information sequence is generated based on information and thesequence, and wherein the spread information sequence is mapped to theresource block.
 17. The base station of claim 16, wherein the sequenceis a cyclically shifted sequence.
 18. The base station of claim 13,wherein a first sequence, a second sequence, and a resource block aredetermined from a resource index, wherein a two-dimensional spreadinformation sequence is generated based on information, the firstsequence and the second sequence, and wherein the two-dimensional spreadinformation sequence is mapped to the resource block.
 19. The basestation of claim 18, wherein the first sequence is a cyclically shiftedshift, and wherein the second sequence is an orthogonal sequence.